Marina waste-conversion plant changes food waste into compost, biogas

A spotless white roof bulges above a small industrial building with four compartments and four fuchsia-colored doors at the Monterey Regional Waste Management District's sprawling, 400-acre complex north of Marina.

The nearly completed building represents a five-year pilot project that combines German technology, a Northern California waste-system developer and the Peninsula solid-waste district.

It houses a new $1.6 million plant to convert food waste from hotels, restaurants and universities in Monterey and Santa Cruz counties into compost and biogas, primarily energy-producing methane gas, in a three-week process.

"We're quite excited about it," said William Merry, general manager of the waste district.

The waste-conversion plant, which will be the first of its kind operating in California when it goes online in mid-February, will be recognized Friday with an opening event complete with a German-style lunch.

"It's a project of national interest," Merry said.

The only other waste-to-compost-and-energy plant in the United States using the same "dry anaerobic digestion" process is at the University of Wisconsin in Oshkosh, Wis. There are more than 30 in planning stages in California, and a few under construction in San Jose, South San Francisco and Oxnard.

The waste district, at the urging of several large Peninsula hospitality businesses, began open-air composting of food waste four years ago. But the new system offers not only a neater process with fewer emissions, but a far quicker production of energy.

The plant, which will be able to handle about 5,000 tons of waste a year, should produce enough power to sell 100 kilowatts of electricity daily to the nearby wastewater treatment plant operated by the Monterey Regional Water Pollution Control Agency.

"We're off the grid here," Merry said. "The power will be sold over the fence."

About 15 plants using the same technology are in use in Europe, operated by waste haulers, small communities and schools.

In response to the growing demand to reuse resources and reduce landfill dumping, there are plenty of technologies out there.

Merry said he recently attended an industry conference and estimated "there are probably 600 different options."

But the dry anaerobic digestion process, which uses special bacteria sprayed on the waste to do their thing, has undergone a statewide environmental review, making it easier to do pilot projects like the Marina plant.

Each compartment in the Marina plant will be able to handle 65 tons of a porous, 50-50 percent mixture of food and yard waste, which will be heated to about 130 degrees.

The plant, which will be operated by the waste district, will be a slow-moving experiment to determine which variables — such as the "feed stock" ratio of food and yard waste — produce the best results.

Dirk Dudgeon of Zero Waste Energy, the plant developer, said a similar plant in the works in San Jose will be able to handle 84,000 tons of waste a year.

A South San Francisco plant will produce high-quality fuel gas to power the garbage trucks that collect the food waste, he said.

Jeff Lindenthal, district recycling manager, said the new plant is another example of "looking at waste as a resource."

The district last year received about 2,600 tons of food waste for its composting program, about the same tonnage the new plant will be able to handle. The plant has a modular design suitable for expansion.